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)(25,26,31,36)(27,32,38,40)(28,34,37,39)(29,35,30,33)(1,3,5,8)(2,6,4,7)(9,11)(10,14)(12,19)(13,18)(15,23)(16,22)(17,20)(21,24)(25,27)(26,32)(28,29)(30,37)(31,38)(33,39)(34,35)(36,40)(9,12)(10,15)(11,17)(13,20)(14,21)(16,24)(18,19)(22,23)(26,33)(28,37)(29,30)(32,39)(34,40)(35,36) involution — undirected(1,2,5,4)(3,7,8,6)(12,20)(15,24)(17,19)(21,23)(25,28,31,37)(26,34,36,39)(27,29,38,30)(32,35,40,33)(1,4,5,2)(3,7,8,6)(10,16)(11,18)(15,24)(17,19)(25,29,31,30)(26,35,36,33)(27,37,38,28)(32,39,40,34)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.