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