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