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