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