One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,14,15)(11,19,20,16)(12,13,18,17)(21,23,24,22)(25,26,30,34)(27,31,37,40)(28,29,33,32)(35,36,39,38)(1,2)(3,7)(4,5)(6,8)(10,15)(11,20)(12,18)(22,23)(25,27,30,37)(26,31,34,40)(28,35,33,39)(29,36,32,38)(2,5)(6,7)(10,15)(13,17)(16,19)(22,23)(25,28,30,33)(26,32,34,29)(27,35,37,39)(31,38,40,36)(9,11)(10,16)(12,21)(13,22)(14,20)(15,19)(17,23)(18,24)(25,27)(26,31)(28,35)(29,36)(30,37)(32,38)(33,39)(34,40) involution — undirected(1,3,4,8)(2,6,5,7)(9,12,14,18)(10,17,15,13)(11,21,20,24)(16,23,19,22)(25,26)(27,31)(28,32)(29,33)(30,34)(35,38)(36,39)(37,40)(1,2)(3,6)(4,5)(7,8)(9,13,14,17)(10,18,15,12)(11,22,20,23)(16,24,19,21)(25,29,30,32)(26,33,34,28)(27,36,37,38)(31,39,40,35)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.