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