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