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