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