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