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