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