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