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