One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,14,17)(11,18,15,12)(13,21,22,16)(19,20,23,24)(26,31)(27,34)(28,36)(37,39)(3,7)(5,8)(9,11,14,15)(10,12,17,18)(13,19,22,23)(16,20,21,24)(25,26,30,31)(27,29,34,32)(28,33,36,38)(35,37,40,39)(1,2)(3,5)(4,6)(7,8)(9,12)(10,15)(11,17)(13,20)(14,18)(16,23)(19,21)(22,24)(25,27,30,34)(26,32,31,29)(28,35,36,40)(33,39,38,37)(1,3)(2,5)(4,7)(6,8)(9,11)(10,12)(13,19)(14,15)(16,20)(17,18)(21,24)(22,23)(25,26)(27,32)(28,33)(29,34)(30,31)(35,39)(36,38)(37,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,12)(10,15)(11,17)(13,20)(14,18)(16,23)(19,21)(22,24)(25,28)(26,33)(27,35)(29,37)(30,36)(31,38)(32,39)(34,40) involution — undirected(9,13)(10,16)(11,19)(12,20)(14,22)(15,23)(17,21)(18,24)(25,29,30,32)(26,34,31,27)(28,37,36,39)(33,40,38,35)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.