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