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