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