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